Free cable winch

ABSTRACT

The invention relates to a free cable winch. Each pair of jaws 11, 14 is guided by two pairs of rollers 18 which run in guideways 1a, 2a formed in the cheeks of the winch case to ensure rectilinear traction of the cable C, with substantially no flexing of the cable between the two pairs of jaws. The invention can be applied to powerful winches with consequent low wear of the cable.

United States Patent 11 1 [111 3,732,598 Hatay 1 51 May 15, 1973 [54] FREE CABLE WINCH [56] References Cited [75] Inventor: Charles Hatay, Bufingen Bei, Ger- UNITED STATES PATENTS many 2,803,456 8/1957 Powers ..226/l64 [73] Asslgnee: necauv'ne come, France 2,990,160 6/1961 Foley ..2s4/134.3 R [221 Fi1ed= July 29,1971 p imaiy'is'x mm g g m 1 Grifi'in' [21] Appl. No.: 167,392 Attorney- Richard C. Sughrue et al. Foreign Application Priority Data [5 7] ABSTRACT The invention relates to a free cable winch. Each pair 7 July 29, 197i) France "70217876 of jaws 11 14 is guided by two pairs of rollers 18 52 U s (:1 24/68 1) 226/164 254/134 3 R in-geliqways [5}] B65h the winch case to ensure rectilinear traction of the [58] Field 6 1 3656 ;11111112113126 i/i iils' 226/163 cable .W tant no fl xi 0f the cable between the two pairs of jaws. The invention can be applied to powerful winches with consequent low wear of the cable.

19 Claims, 6 Drawing Figures PAIENIEU MAY 1 5 m5 SHEET 2 BF 3 PAIEN 1m 1 $1973 SHEET 3 0F 3 FREE CABLE WINCH The present invention relates to a freely portable cable winch controlled by two external levers, one for traction, and the other for release or unwinding of a load, which permit good response to the requisite conditions for the rational use of this type of apparatus, that is:

a. Completely rectilinear traction of the cable through the interior of the apparatus.

b. Sealing of the casing of the apparatus with a view to protecting the mechanism from abrasion.

c. High mechanical output.

(1. Provision of easily interchangeable wearing parts.

e. Minimum weight and volume of the apparatus compatible with a high degree of safety.

f. The possibility of complete and rapid opening of the case with a view of maintenance of the mechamsm.

It is to be understood that the invention could be used with rope or steel cables.

Known freely portable cable winches comprise as organs of traction and of release, a cable (loaded or not), two clamps arranged for simultaneous and opposite longitudinal movement with respect to each other, now sliding along the cable and now gripping it. The clamps of the known apparatus each comprise two pairs of driving rods controlled by cams, two cams, and two jaws for gripping the cable.

Each of the two clamps of the known freely portable cable winch is solidly connected to a pair of dragging rods, by articulation of the extremities of two pairs of short levers of the clamp under consideration, on two fixed axes positioned, at one extremity of the pair of corresponding rods. The two pairs of rods have different lengths, and are articulated on the two opposite ends of a crank which oscillates on a central axis.

The longitudinal axis of the jaws of a clamp is in this manner linked to the angular movements of its pair of control rods, from which it results that when the clamps are displaced alternately, then the longitudinal axes of the pairs of jaws of the said clamps, never have a rectilinear trajectory, and are never coaxial with each other. Besides that, the axes of the jaws, by their continual inclinations, impose a double torsion on a short length of the cable (which is sliding under load) which produces an accelerated wear of the cable and a loss of output from the winch.

The invention will be better understood from the following description of the accompanying drawings, which is given by way of example only.

FIG. 1 is a view in elevation, of a freely portable cable winch, the front cheek being partially cut away to show the internal mechanism,

FIG. 2 is a sectional plan view taken on the line Y-Y in FIG. 1,

FIG. 3 is a sectional plan view taken on the line Z-Z' in FIG. 1 (control axles for the clamps not being sectioned),

FIG. 4 is a sectional elevation taken on the line X-X in FIG. 1,

FIG. 5 is an elevation view partly in section showing a clamp of the apparatus, and

FIG. 6 is a plan view of the clamp shown in FIG. 5.

The freely portable cable winch in accordance with the invention shown in FIGS. 1 to 4 comprises a casing made in sheet steel, and constituted by a rear cheek or wall 1, a cheek 2, and a cover 3 forming the base of the case. A crank 4, controlled from the exterior of the case by a traction lever 5, oscillates in two bearings, the one bearing 6 being fixed on the cheek l, and the other bearing 7 being fixed on the cheek 2. The crank 4, comprises two opposed bosses 4a and 4b, symmetrically arranged with respect to the central control axis 40.

On the boss 4a, is articulated by means of an axle 8, a pair of parallel rods 9, controlling the clamp remote from the crank, which clamp will in its entirety be designated B. On the boss 4b is articulated by another axle 8, a pair of rods 10, controlling a clamp A, which is nearer to the crank 4 than the clamp B.

Each clamp A and B constitutes an arrangement of the type already described in the German Patent of the same applicant No. l,263,259, and comprises a means of clamping and guiding for the cable (designated C) which means comprises a U-shaped jaw 11 referred to as the main jaw. This jaw can be constituted in one, two or three pieces assembled together, which in any case present in the lower portion of the U, a semicircular internal bearing surface for the cable C. The piece which forms the co-operating part is vertically movable for clamping or de-clamping of the said cable C, placed in the interior of the U, and this piece is constituted by a jaw 12, better described hereinafter, which jaw receives the clamping pressure of a pair of cams 13, (which can be formed according to different known profiles) arranged transversely to the side walls of the jaw 11. The cams 13 exercise their pressure on the jaw 12 and take also reaction bearing on appropriately profiled surfaces in the said side walls of the jaw 11 so that the cams act between the main jaws 11. The oscillatory movement of cable gripping and of traction of the load is transmitted to the cams 13 of each clamp by two pairs of short levers, of which one 14 is double acting, having an upper extension 140, and the other 15 is simple acting. The keying drive is obtained by direct casing of the profile of the cam in appropriately shaped openings of the short levers 14 and 15.

The cable C, clamped between the pairs of jaws 11 and 12, of the two clamps A and B, traverses the apparatus longitudinally; the cable entrance being effected by the ferrule or grommet 16, and the exit comprising first a passage through an opening at the center of the crank 4, and then a hole formed through the axis of a towing or anchoring hook 17. The said hook 17 encased between the checks 1 and 2 as will be more fully described, freely pivots on its own axis. The total retaining effort of the load of the apparatus is supported by a bearing collar 17a of the hook 17 which engages against an end wall of the case.

The method according to the invention whereby there is obtained the rigorous rectilinear and coaxial drive movement of the pairs of jaws of the clamps A and B, in their alternating opposed movements, is achieved by an assembly of parts of which the combination permits particularly of the adaptation of very economic wearing parts which are easily interchangeable made in a metal adapted to produce a high driving power on the cable.

The construction is characterized by the following features:

1. The pressure earns 13 shown in FIGS. 1,2,5 and 6 include an extension from each side of their lateral faces of two concentric stub shafts, formed from the mass of the cam, the circular section of which is entirely circumscribed within the profile of the cam. It should be understood however that the invention also includes within its scope stub shafts which have a section less than that of a full circle. The shafts 13a on both sides of the common plane of the rods 9 and 10, so as to constitute, on the outsides of the said common plane, four axles of rotation of four flanged guide rollers 18, for guiding the main jaws 11 of each of the clamps. The guiding of the clamp assembly thus obtained is effected by running of the rollers 18 in two laterally projecting but rectilinear slideways (best seen in FIGS. 2 and 4) dished symmetrically, the one 1a in the cheek 1,

the other 2a in the cheek 2. 2. With a view to permitting the guiding of the shafts 13a, outside the common plane of the rods 9 and 10, during movement of the pair of rods 9, controlling the clamp B, the contour outline generated by the projection on each side of the clamps A and B of the four axles 13a (which produces an increase of the volume and weight of the case) the pair of rods 9, each provides in effect an elongated longitudinally arranged opening 9a, through the interior of which at least two, but preferably four, of the said shafts 13a project. At the same time the two clamps can move freely in the said openings 9a which are of a width adapted to that which is required by the respective positions of the clamps A and B and of the pair of rods .9.

3. For permitting the transmission of synchronous movements of the same amplitude to the two pairs of small levers with parallel axes of the clamps B and A, respectively by the pairs of connecting rods 9 and 10, of which the longitudinal movements alternate, combined with their angular movements, the manner of coupling of the connecting rods and small levers to produce this effect is the following:

Each pair of rods 9 and 10, is joined to two pairs of small levers, of its respective clamp, by two articulation axles l9 and 20. The axle 19 is placed at the extremity of a pair of connecting rods, in a fixed position. On the said axle 19, there is articulated between the elements of the pair of rods, that pair of small levers of the respective clamp, the furthest from the crank 4. The axle 20, placed to the rear of the axle 19, is movably mounted in some openings cut in the flanks of the rods of each pair, to provide a movement in the form of an arc of a circle, of which the center is the axis of the axle 19 and the radius r2, shown in FIG. 1, is equal to the distance between centers of the axles 13a, of the pair of cams of each clamp.

The openings 9a and a of the pairs of rods 9 and 10, have the form of a sector of an annulus, of which the sides are the arcs of circles of radius r1 and r2 respectively, and of which the center is the axis 19.

The sliding of the axles 20 in the said openings 9a and 10a, is effected by the intermediary of two bearing pads 21, which are articulated at the two extremities of the axle 20. The bearing pads 21 are made in nitrided steel, having a form of a sector of an annulus adapted to the form of the openings, and are able to slide freely in the angular play provided in the said openings 9a and 10a. The said bearings 21 are furnished with a retaining lip which lips engage face-to-face with the insides of the elements of each pair of rods (see FIG. 3).

On the. movable shaft 20, maintained equidistant from the shaft 19, is articulated the pair of small levers of each clamp the nearest to the crank 4, that is the pair 14 for the clamp B, and the pair 15 for the clamp A.

It will be readily apparent that an arrangement adapted to the oscillating small levers permits a rigorous rectilinear and coaxial control of the clamps A and B, which are furnished besides with their guiding arrangements. In addition to the advantage of driving the cable without destructive flexings, this mode of rectilinear traction, permits without inconvenience, the extrapolation of this type of apparatus by the possibility of extending at will the length of the jaws, which elongation is an imperative requirement for the traction of cables of large diameters, hauling strong loads.

It should also be understood-that it is possible to invert the respective positions of the axes 19 and 20 with respect to the pairs of small levers of the clamps without departing from the scope of the invention.

4. The jaws 12 of the clamps by their double role on the one part as receiving members of unitary very high pressure transmitted by the earns 13 are made in steel of high quality characteristics and, on the other hand, the entraining members for the cable demand on their part mechanically contradictory qualities. 0n the one hand, at the pressure reception, a steel treated to produce great hardness for resisting the high pressure of the cams l3, and a soft steel or an autenitic steel with a gripping tendency for the easy control and nonslipping of the cable. To this end, the jaws 12, shown in FIG. 5, are formed in two parts, providing between them a transversal socket of a dovetail form, the which profile is obtained by forming the jaws in long lengths by a hot extrusion and subsequent cutting off, which is a very economical method of production.

The main body 12, has a female dovetail completed by an inclined form of sides as shown in FIG. 5. This body 12 is in steel of high resistance. The slipper driver 12a for the cable is furnished with a counterpart male dovetail, which engages without play in the main body. This slipper 12a, as indicated above, is in soft or austenitic steel. The inter-changeability of the slipper 12a, is easy, and its disengagement in functioning impossible, due to the fact that it is enclosed in the U of the main jaw 11.

The freely portable cable winch of known type, presents the serious inconvenience of a long opening not protected, positioned in the top axial part of its case. This opening is provided for the external releasing lever, which is coupled with the upper extensions of the master short levers of each of the clamps as isthe case in the known apparatus. The said lever of the known method of connection by its combined external movements at the same time longitudinal and oscillatory, necessitates for its top opening in the case.

3 A feature of construction of the free cable winch herein described aims at obtaining the sealing of the opening of the axial passage of the external release control lever, by utilization of appropriate arrangements of parts permitting on the one hand the reduction to the minimum of the length of the opening, and of displacement of the said lever, and on the other hand, the obtaining of permanent sealing of the said opening. These arrangements are as follows:

The upper extensions 14a of the pairs of levers 14, of each of the clamps A and B, are joined by a shaft 22, having a double function:- (a) providing a driving axle for the pair of levers 14a, for the purpose of release, (b) the carrying and guiding of a pair of parallel supports 24 having two longitudinal openings 24a and 24b which are traversed by the shafts 22, of the clamps A and B. The supports are disposed parallely to the common external or internal planes of the short levers 14, of the two clamps A and B. The preferred position is on the outside of these levers as shown in FIG. 1. For this purpose, the axles 22 are extended by external engagement in the openings 14a and 14b, the free displacement in the said openings being effected by rings 23 on the axles 22.

The central parts of the two supports 24, are connected and spaced apart by a shaft 25 on which oscillates in the space between the supports, a lever 26 controlling exteriorally the cable release movement of the apparatus. On the lever 26 are symmetrically arranged with respect to the axle 25, two axles 27 and 28, which are driving members for two pairs of links, that is links 29 connected to the pair of top levers 14a of the short levers 14, of the clamp A, and links 36 connected to the pair of rods 14a corresponding to the clamp B.

As shown in FIG. 1, the pair of supports 24 are capable of free displacement in the longitudinal sense to adapt themselves always to the variable inclination of the pairs of master short levers 14, without any constraint on the latter. These variations of inclination of the said short levers take up the diametrical wear of the cable of the apparatus. The inclination at the commencement of operation is determined by the state of diametrical wear of the cable being used, the shaft 25 of the release lever 26, is not, during the operations of traction or release submitted to sudden appreciable longitudinal displacements or angular displacements of the lever 26. This reduction of movement of the axle 25 has repercussions on the displacement of the said lever 26, and permits the reduction of the length of the opening necessary for the said movement of the lever 26.

6. The opening for the passage of the lever 26 can be enclosed in a plane surface of a length at least twice that of the said opening.

7. The preferred method shown in FIG. 1, comprises the inclusion of the opening 1b 2b, in the top part of the case, situated above the axis of the median zone of oscillation of the shaft 25 of the lever 26. The said top part of the casing has the form of an arc of a circle, constituted by two symmetrical pressed portions of the cheeks 1 and 2. At the top of the arc of the circle, is arranged an opening 1b 2b formed in equal halves in the said cheeks l and 2, the which opening is adequate for the extreme displacements of the lever 26. On the interior surface of the arc the top part of the casing is adapted for the low friction alternating angular movement of a thin piece 31 formed in the arc of a circle, abutting on the said interior surface with a view to constitute the sealing organ of the opening 1b 2b. This piece 31 is moulded in plastics material, or in any other material having a low coefficient of friction without greasing, for example in a plastics material known under the trade name RILSAN.

The piece 31 is furnished with a small opening 31a, permitting the passage in all positions of inclination of the lever 26. The supple adherance of the piece 31 against the top member of the case is obtained by magnetic effect and to this end, some magnets 32 are fixed on the piece 31. The coercive force of the said magnets for the support of the piece 31 on the soft steel sliding surface of the case is calculated so that the effort of movement of the said piece 31 by the oscillations are minute. The obstruction of the opening lb 2b, is total in all positions owing to the length of the piece 31 when in its extreme positions in view of a large covering of the said opening.

8. The supple adherance of the piece 31 against the top surface of the casing can be obtained by pressure of compression springs (not shown in the drawings), which springs take bearing on the release lever of release 26, on the inside of the casing.

9. The simultaneous opening of two pairs of jaws 11 and 12 of the clamps A and B is obtained by traction exercised at that end of the pair of supports 24, nearest to the crank 4. For this purpose, each of the supports 24 is furnished with an opening 24c, and between the said openings 24c, face-to-face with the inside faces of the supports 24 is transversely placed a traction axle fixed to the end of a rod 33, itself articulated at its other end on a transverse axis 34a, fixed on a handle 34. The handle 34 has a double usage, that is on the one hand it permits easy and balanced carrying of the apparatus, and on the other hand by pivoting on the hinge pin 34b, it constitutes a powerful opening lever for simultaneous opening of the two pairs of jaws of the clamps A and B, with a view to the easy introduction between the said pairs of jaws of the traction cable of the load.

The security locking of the handle 34, is constituted by a latching assembly 35 with automatic closing.

The assembly of operating mechanism above described is completed by arrangements for automatic application of clamping of the clamps of a known type, constituted for the clamp A by a compression spring 36 taking bearing on an angle iron 37, solid with the cheek 1, and exercising a continual pressure on the clamp A, through a bearing cap 38, made in sheet steel, bridging the pair of extensions 14a of the levers 14. For the clamp B, the arrangement is constituted by a fixed bearing member 39 serving also as a bracing member between the cheeks 1 and 2. A compression spring 40, guided by a rod 41, exercises a continual bearing pressure on a bearing bar 42, solid with the bottom part of the jaw 11 of the clamp B.

In the known free cable winches, the thickness of the sheet steel of the case is uniform, and is calculated on the resistance to traction and the deformation which would be presented by a very weak portion of the surface of the case directly concerned in the effort of traction, the said portion of surface of the case concerned being situated between the bearing collar of the retaining book of the apparatus and the carrier bearings of the central shaft of the crank. From this it results that the rest of the surface of the case not concerned by the local effort, is made with an excessive thickness of sheet steel, which causes a useless dead weight.

The method of construction herein described has the following aim:

On the one hand the lightening of the case, and on the other hand a fixation with great robustness of the hinges of a bottom cover of the case with a full opening necessitating the articulation of the said hinges in the immediate proximity of the towing hook.

The arrangement is the following:

10. Two symmetrical shells 43 and 44, made in thick sheet steel pressed into a form necessary for boxing respectively in the cheeks l and 2 comprising on their lateral portions a bore hole permitting their common riveting on the said cheeks 1 and 2, having the bearings 6 and 7, of the axle 4c, of the crank 4. The symmetrical parts in angle iron of the shells 43 and 44, each comprise a semi-circumferential covering jointly arranged under the bearing collar 17a of the towing hook 17. This arrangement permits the support in a rational fashion of the transmission of the traction effort exercised by the axis 4c of the crank on the carrier of the collar 17a, by the two shells 43 and 44 only.

The rigidity of the shells permits the utilizing of them as supports for the hinge. To this end, each shell has formed on itself coincident with the end of an opening at the bottom of the case in each of the cheeks l and 2, a male semi hinge 43a for the shell 43, and 44a for the shell 44, the which semi hinges are not shown on the drawing but are placed on one side and the other of the female hinge 3a of the base cover shown in FIGS. 1 and 3. The said cover 3, is maintained in closed .position by a bolt forming the hinge pin, a bolt at the extremity, and a central bolt, of which the locking is rendered particularly effective by its clamping on the stop 39, which constitutes a cross member between the cheeks 1 and 2.

FUNCTIONING.

The free cable winch according to the invention does not have any difference in its cycling function from the known cable winch.

What we claim is:

1. A free movable winch wherein there are opposed clamps controlled by two external levers, one lever for traction, and the other for release or unwinding of the cable, each of the clamps having two cams for applying the cable-gripping pressure to the jaws of the clamp, a part of at least some of the cams projecting laterally outside the jaws and providing axles carrying guide rollers which engage in rectilinear longitudinal guideways formed in the case of the apparatus, thus providing rectilinear and coaxial movement of the jaws of the clamps.

2. A free cable winch as claimed in claim 1, in which each of the axles projecting laterally from the cams, are cut out from the mass of material from which the cam is formed, and has a substantially circular cross-section, which is completely circumscribed by the cam profile.

3. A free cable winch as claimed in claim 1 in which I the clamps are operated from the oscillation of the traction lever through a crank and twopairs of parallel connecting rods, one pair for each clamp of the apparatus, there being an elongated opening formed in each of the connecting rods associated with the clamp furthest from the crank, the axles projecting from the cams passing through these openings.

4. A free cable winch as claimed in claim 1, in which the center distance between the axes of the two transverse axles of each clamp is equal to the center distance between the axes of the cams of that clamp.

5. A free cable winch as claimed in claim 1, in which each clamp has a substantially U-shaped main jaw which at least partially embraces the cable, and a movable jaw located within the legs of the U-shaped main the lower part of the movable jaw is made in soft steel.

8. A free cable winch as claimed in claim 6 in which the two parts of the movable jaw are connected by a dovetail joint.

9. A free cable winch as claimed in claim 1, in which the release lever is pivoted on a pivot shaft extending laterally between a pair of parallel longitudinally extending supports which are carried on cross shafts each coupling upper extensions of one pair of small levers of each clamp, the two cross shafts extending through elongated openings in the supports, whereby the small levers can be oscillated by the normal traction movement without moving the release lever, whereby the length of the case can be kept to a minimum.

10. A free cable winch as claimed in claim 9, in which the release lever has two links pivoted to the release lever on opposite sides of its own pivotal axis, and connected at their other ends to the cross shafts of the small levers.

11. A free cable winch as claimed in claim 9, in which a link rod extends between a handle pivoted to the outside of the case, and a transverse rod sliding in slots in the two parallel supports, the handle having an automatic latching arrangement with the case at its free end, this handle serving the dual purpose of a carrying handle for the winch and a lever which can turn on its pivot to transmit a motion through the supports to the upper extensions of the small operating levers so as to produce simultaneous opening of the jaws of the two clamps for introducing the cable into the apparatus.

12. A free cable winch as claimed in claim 1, in which the case containing the moving parts has an opening for the release lever which opening is formed in a plane surface of at least twice the length of the opening.

13. A free cable winch as claimed in claim 1, in which the upper part of the case is formed into an arc of a circle drawn about the pivotal axis of the release lever when the latter is in the central position, there being a sealing member engaging with the internal curved surface of this upper part of the case, and being adapted to slide on that surface, the release lever passing through the sealing member so that the latter slides with rocking movement of the release lever.

14. A free cable winch as claimed in claim 13, in which the length of the sealing member is such that it closes the top opening of the case in all positions of the release lever.

15. A free cable winch as claimed in claim 13 in which the sealing member is made in plastics material but it held against the surface of the case by magnets fixed to the sealing member, the coercive force of which is calculated so that the resistance to sliding of the sealing member is minute.

16. A free cable winch as claimed in claim 1, in which there is a pair of shells each having a wall which is adapted to be fixed to the inside of a corresponding wall.

17. A free cable winch wherein there are opposed clamps controlled by two external levers, one lever for traction and the other for release or unwinding of the cable, each of the clamps having two pairs of small operating levers, each pair of which is connected by means of a transverse axle to a pair of control connecting rods driven by a crank operated by the traction lever, one of the transverse axles of each clamp being fixed relatively to its small operating lever, but the other having limited movement relatively to its operattwo ends by slide blocks the exterior shape of each of which is that of a sector of an annulus, the slide blocks being located for limited angular sliding motion in openings formed in respective operating levers, the slide block being located laterally by lips engaging with the inner faces of their respective operating levers.

t k k 

1. A free movable winch wherein there are opposed clamps controlled by two external levers, one lever for traction, and the other for release or unwinding of the cable, each of the clamps having two cams for applying the cable-gripping pressure to the jaws of the clamp, a part of at least some of the cams projecting laterally outside the jaws and providing axles carrying guide rollers which engage in rectilinear longitudinal guideways formed in the case of the apparatus, thus providing rectilinear and coaxial movement of the jaws of the clamps.
 2. A free cable winch as claimed in claim 1, in which each of the axlEs projecting laterally from the cams, are cut out from the mass of material from which the cam is formed, and has a substantially circular cross-section, which is completely circumscribed by the cam profile.
 3. A free cable winch as claimed in claim 1 in which the clamps are operated from the oscillation of the traction lever through a crank and two pairs of parallel connecting rods, one pair for each clamp of the apparatus, there being an elongated opening formed in each of the connecting rods associated with the clamp furthest from the crank, the axles projecting from the cams passing through these openings.
 4. A free cable winch as claimed in claim 1, in which the center distance between the axes of the two transverse axles of each clamp is equal to the center distance between the axes of the cams of that clamp.
 5. A free cable winch as claimed in claim 1, in which each clamp has a substantially U-shaped main jaw which at least partially embraces the cable, and a movable jaw located within the legs of the U-shaped main jaw.
 6. A free cable winch as claimed in claim 5, in which the movable jaw is made in two parts adapted for detachable connection, the upper part being made in steel of high mechanical resistance to receive the pressure of the cam, and the lever part being made in material which is adapted to grip the cable.
 7. A free cable winch as claimed in claim 6, in which the lower part of the movable jaw is made in soft steel.
 8. A free cable winch as claimed in claim 6 in which the two parts of the movable jaw are connected by a dovetail joint.
 9. A free cable winch as claimed in claim 1, in which the release lever is pivoted on a pivot shaft extending laterally between a pair of parallel longitudinally extending supports which are carried on cross shafts each coupling upper extensions of one pair of small levers of each clamp, the two cross shafts extending through elongated openings in the supports, whereby the small levers can be oscillated by the normal traction movement without moving the release lever, whereby the length of the case can be kept to a minimum.
 10. A free cable winch as claimed in claim 9, in which the release lever has two links pivoted to the release lever on opposite sides of its own pivotal axis, and connected at their other ends to the cross shafts of the small levers.
 11. A free cable winch as claimed in claim 9, in which a link rod extends between a handle pivoted to the outside of the case, and a transverse rod sliding in slots in the two parallel supports, the handle having an automatic latching arrangement with the case at its free end, this handle serving the dual purpose of a carrying handle for the winch and a lever which can turn on its pivot to transmit a motion through the supports to the upper extensions of the small operating levers so as to produce simultaneous opening of the jaws of the two clamps for introducing the cable into the apparatus.
 12. A free cable winch as claimed in claim 1, in which the case containing the moving parts has an opening for the release lever which opening is formed in a plane surface of at least twice the length of the opening.
 13. A free cable winch as claimed in claim 1, in which the upper part of the case is formed into an arc of a circle drawn about the pivotal axis of the release lever when the latter is in the central position, there being a sealing member engaging with the internal curved surface of this upper part of the case, and being adapted to slide on that surface, the release lever passing through the sealing member so that the latter slides with rocking movement of the release lever.
 14. A free cable winch as claimed in claim 13, in which the length of the sealing member is such that it closes the top opening of the case in all positions of the release lever.
 15. A free cable winch as claimed in claim 13 in which the sealing member is made in plastics material but it held against the surface of the case by magnets fixed to the sealing member, the coercive force of which is calculated so that the resistance to sliding of the sealing member is minute.
 16. A free cable winch as claimed in claim 1, in which there is a pair of shells each having a wall which is adapted to be fixed to the inside of a corresponding wall.
 17. A free cable winch wherein there are opposed clamps controlled by two external levers, one lever for traction and the other for release or unwinding of the cable, each of the clamps having two pairs of small operating levers, each pair of which is connected by means of a transverse axle to a pair of control connecting rods driven by a crank operated by the traction lever, one of the transverse axles of each clamp being fixed relatively to its small operating lever, but the other having limited movement relatively to its operating lever in an arc about the axis of the first fixed axle.
 18. A free cable winch as claimed in claim 17, in which the transverse axle of each clamp which is further from the crank is fixed and the transverse axle of each clamp which is nearer to the crank is movable.
 19. A free cable winch as claimed in claim 18, in which the movable transverse axle is articulated at its two ends by slide blocks the exterior shape of each of which is that of a sector of an annulus, the slide blocks being located for limited angular sliding motion in openings formed in respective operating levers, the slide block being located laterally by lips engaging with the inner faces of their respective operating levers. 